We propose a prospective placebo controlled study to investigate the safety and efficacy of 25 mg MIX applied subcutaneously once weekly in patients with active UC, who are either steroid dependent or are intolerant or not responding to azathioprine/6-mercaptopurine therapy or have no response/ lost response to infliximab prior to the study inclusion. In the setting of an implementation-planning (U34) grant we finalized the study protocol and associated formal requirements for this trial. We obtained a lead IRB approval and are currently obtaining IRB approvals of the participating sites. We registered an IND number (108,560) with the FDA and established the study infrastructure for this prospective placebo-controlled multi-center study using the center framework of the Crohn's and Colitis Foundation of America (CCFA) Clinical Research Alliance (CRA). The Specific Aims of the trial are: 1) To evaluate the safety and tolerability of 25 mg MTX applied sq once weekly over a time period of 48 weeks. 2) To evaluate the relapse-free survival of MTX maintenance therapy compared to placebo over a time period of 32 weeks. 3) To evaluate the efficacy of MTX over a time period of 16 weeks to induce steroid free remission. 4) To establish a DNA, plasma and serum library to enable the evaluation of clinical and pharmacogenomic models to predict the response to MTX therapy in patients with UC.